The external bottom bracket is available with two different bearing options.. Optimized for road use. . All common systems are covered with this upgrade unit - making it ideal for Shimano, Race Face, and others. . The machined aluminium cups hold either full stainless steel cartridge bearings, or ceramic bearings in stainless races. . These custom, Swiss made bearings are double sealed, fully serviceable and removable which give much greater life span than stock units. . The bearings are made (as all our bearings are) by INA and have been designed to run directly on the crankset axle, without the use of shims or spacers - again increasing life and reliability. . We use a non contact, free running labyrinth seal to protect the bearing externally, and the machined aluminium centre tube is sealed internally with o-rings. . Standard 6 colours are available on cups - red, blue, silver, black, gold and gunmetal, with the centre tubes being black on the stainless and gunsmoke on the ceramic.. English thread.